Police and nurses unions joined the fight yesterday, donning T-shirts that said "stop the cell off no prisons for profit", swelling protest numbers to about 2000.

Prison officers called a 24-hour stop work on Wednesday night, forcing NSW jails into lockdown and court schedules into turmoil.

Newcastle District Court had to adjourn six matters yesterday because there was nobody to take inmates to court.

The people who would usually escort them from jail were in the march from Hyde Park to Macquarie Street, where they stopped outside the gates of Parliament.

The crowd roared with chants of "sack Ron Woodham" and Cessnock prison officers spoke of a sense of betrayal that John Robertson, who used to lead such protests, was now in charge of the privatisation as Corrective Services Minister.

Cries for Mr Robertson to face the protesters went unmet, but Mr Robertson faced a media crowd about two hours later to talk about the government's plans.

He shrugged off questions about whether it was ironic that he was leading the push for privatisation, when he led the battle against privatising electricity less than a year ago.

Mr Robertson said there would be no job losses and taxpayers would save $63 million.

He also denied there was any privatisation, instead describing it as "outsourcing".

"Privatising is selling assets. And we are keeping the bricks and mortar," he said.

Mr Robertson said prison workers could transfer to other jails in NSW, take redundancy or apply for work with the new operator.

When asked if Commissioner Woodham's job was safe, Mr Robertson said the commissioner was doing a "fantastic job".

But in a clear sign the issue has caused a major rift within the NSW Government, Labor whip Gerard Martin told the protesters that privatisation went against ALP policy and could not be tolerated.

"We will take on the executive Government to defend the Party platform," he said.

Labor MPs Kerry Hickey and Paul Gibson also joined the protesters, giving speeches from the platform.